P1441

Diagnostic Chart:

Wiring Diagram:

System Description

The evaporative system includes the following components:

^ Fuel tank

^ EVAP vent solenoid

^ Fuel tank pressure sensor

^ Fuel pipes and hoses

^ Fuel vapor lines

^ Fuel cap

^ EVAP canister

^ Purge lines

^ EVAP canister purge valve

^ EVAP service port.

The evaporative emission system is checked by applying vacuum to the EVAP system and monitoring for a vacuum decay. The PCM monitors the vacuum level through the fuel tank pressure sensor signal.

At an appropriate time, the EVAP canister purge valve and the EVAP vent solenoid are turned ON, allowing the engine to draw a small vacuum on the entire evaporative emission system. After the desired vacuum level has been achieved, the EVAP canister purge valve is turned OFF, sealing the system.

The EVAP canister purge valve allows manifold vacuum to purge the canister. The Powertrain Control Module (PCM) supplies a ground to energize the solenoid valve (purge ON). The EVAP canister purge valve control is Pulse Width Modulated (PWM) or turned ON and OFF several times a second. The duty cycle (pulse width) is determined by engine operating conditions including load, throttle position, coolant temperature and ambient temperature. The duty cycle is calculated by the PCM and the output is commanded when the appropriate conditions have been met.

The system checks for conditions that cause the EVAP system to purge continuously by commanding the EVAP vent solenoid ON and the EVAP canister purge valve OFF (EVAP vent solenoid CLOSED, EVAP purge PWM 0%). If fuel tank vacuum level increases during the test, a continuous purge flow condition is indicated. This can be caused by the following conditions:

^ EVAP canister purge valve leaking

^ EVAP purge and engine vacuum lines switched at the EVAP canister purge valve

^ EVAP canister purge valve driver circuit grounded

If any of these conditions are present, DTC P1441 will set.

Conditions for Setting the DTC

^ DTCs P0106, P0107, P0108, P0112, P0113, P0117, P0118, P0121, P0122, P0123, P0125, P0131, P0132, P0133, P0134 and P1133 not set.

^ The Barometric pressure (BARO) is greater than 75 kPa.

^ The intake air temperature is between 5°C and 29°C (41°F and 84°F) at engine start up.

^ The engine coolant temperature is between 5°C and 29°C (41°F and 84°F) at engine start up.

^ Intake Air Temperature is not more than 1°C (2°F) greater than the Engine Coolant Temperature at start up.

^ Engine Coolant Temperature is not more than 7°C (12°F) greater than the Intake Air Temperature at start up.

^ Fuel tank level is between 26% and 74%.

^ The Throttle position (TP) sensor is between 9 and 35%.

^ The EVAP solenoid is at 50% PWM within 65 seconds of engine run time.

^ A continuous purge flow condition is detected during the diagnostic test.

Action Taken When the DTC Sets

^ The Malfunction Indicator Lamp (MIL) will illuminate.

^ The PCM will record operating conditions at the time the diagnostic fails. This information will be stored in the Freeze Frame and Failure Records buffers.

^ A history DTC is stored.

^ Coolant fan turns ON.

Conditions for Clearing the MIL/DTC

^ The MIL will turn OFF after three consecutive ignition cycles in which the diagnostic runs without a fault.

^ A history DTC will clear after 40 consecutive warm up cycles without a fault.

^ DTC(s) can be cleared by disconnecting the battery.

Diagnostic Aids

Although this DTC is considered a type A diagnostic refer to Powertrain Control Module, it acts like a type B diagnostic under certain conditions. Whenever this diagnostic reports the system has passed, or if the battery is disconnected, the diagnostic must fail twice before setting a DTC. The initial failure is not reported to the diagnostic executive or displayed on a scan tool. A passing system always reports to the diagnostic executive immediately.

Check for the following conditions:

^ Poor connection at PCM. Inspect harness connectors for the following conditions:

- Backed out terminals

- Improper mating

- Broken locks

- Improperly formed

- Damaged terminals

- Poor terminal to wire connection Damaged harness. Inspect the wiring harness for damage. If the harness appears to be OK, connect the EVAP pressure/purge cart J 41413 to the EVAP service port, pressurize the EVAP system to 10 in. H2O and observe the Fuel Tank Vacuum Pressure display on the scan tool while moving connectors and wiring harnesses related to the EVAP canister purge valve. A sudden change in the display will indicate the location of the fault.

^ Incorrect vacuum line routing. Verify that the source vacuum line routing to the EVAP canister purge valve is correct and that the EVAP purge and source vacuum lines to the EVAP canister purge valve are not switched.

^ Loose Carbon in the purge solenoid. Blow out the lines and replace the purge canister. Refer to Evaporative Emissions System / Service and Repair for further procedure.

Test Description

Number(s) below refer to the step number(s) on the Diagnostic Table.

1. The Powertrain OBD System Check prompts the technician to complete some basic checks and store the freeze frame and failure records data on the scan tool if applicable. This creates an electronic copy of the data taken when the malfunction occurred. The information is then stored on the scan tool for later reference.

2. If an EVAP canister purge valve electrical malfunction is present, the purge system will not operate correctly. Repairing the electrical malfunction will very likely correct the condition that set DTC P1441.

3. Checks the fuel tank sensor at ambient pressure.

5. Forces the fuel tank pressure sensor to re-zero.

7. Verifies that the fuel tank pressure sensor accurately reacts to EVAP system pressure changes.

9. If the EVAP purge and engine vacuum lines are switched at the EVAP canister purge valve, the solenoid valve will leak vacuum.

12. Duplicates the Powertrain On-Board Diagnostic test.